GB1572545A - Crane-carrying platform structures - Google Patents

Description

PATENT SPECIFICATION

( 11) 1 572 545 ( 21) Application No 42035/77 ( 22) Filed 10 Oct 1977 ( 31) Convention Application No.

7 630587 ( 32) Filed 12 Oct 1976 in ( 33) France (FR) ( 44) Complete Specification published 390 Tuly 1980 ( 51) INT CU 5 B 66 C 23/18 ( 52) Index at acceptance B 8 H 553 EA B 8 J 19 B 3 ( 72) Inventors DOMINIQUE MICHEL ALAIN NOBLANC ( 54) CRANE-CARRYING PLATFORM STRUCTURES ( 71) We, COMPAGNIE GENERALE P Ou R LES DEVELOPPEMENTS OPERATIONNELS DES RICHESSES SOUS-MARINES 'C G DOR Is", a French Body Corporate, of 83-85, Boulevard Vincent Auriol, Paris 75013, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statment: The invention relates to crane-carrying platform structures for use over water.

Such structures are commonly mounted on a base resting on the bottom of the sea or other body of water, to support installations generally assembled on the platform for some industrial or scientific purpose, such as for exploration, oil production, or electrical power generation, high above water level The handling operations are carried out with the aid of a crane.

Such a platform structure generally comprises one or a multiplicity of bridges, intended for the installations, at a considerable height above the water, for example metres or more The crane is an essential element of the installation It is useful firstly in the construction of the platform structure which implies that, of necessity, it is one of the first items to be installed.

For preference, it is generally located at a point which is offset with respect to the central shaft which is intended to support the platform, in such a manner that its boom can extend over all parts of the platform and raise installations brought by boats without these having to come too close to the platform.

Thus, this invention is concerned with cranes installed on the platform once this has been finished, but before it is placed on the base However, for reasons of stability and because of the dynamic forces created during transport, the crane cannot be placed at its operational height which is very much above the level of the platform The crane therefore has to be mounted as a deck with its mounting fixed to the platform in a temporary manner, this relationship not being disturbed until 50 the platform and the base have been brought together.

The installation of a self-raising platform with its vertical support and guiderails on the base of a structure has already 55 been envisaged for the construction of works at sea which have to feature a crane mounted on a column which dominates the superstructure The head of the crane support column is constructed subsequently 60 through a hole in this platform and the crane is mounted on it, after which the platform and the crane are raised in keeping with the construction to the height of the This invention proposes another method of installation which makes the crane effectively available at an early stage and, under certain conditions, permits a final positioning of the crane in a shorter time 70 The method of installing a crane according to the invention includes the steps of installing the crane and a mounting therefor upon the platform structure offset from the column-seating area thereof for deck use 75 over and alongside the platform structure, transporting the platform structure to the site of the base and positioning the platform structure to seat upon the column of said base with the crane mounting aligned with 80 a subsidiary offset column in the base, and elevating the crane to a final functional position above the platform structure by raising a shaft in said subsidiary column, which shaft engages the crane mounting 85 The platform is positioned over the base so that the crane is located exactly on the vertical axis of the offset column The shaft element in this offset column can then be raised above the column for the purpose of 90 W) It W) ( 1.1 t_ (n 1 572 545 elevating the crane Figure 8 shows an axial section of the The crane mounting, in its preferred platform structure in its last stage; form includes a depending shaft element Figure 9 shows an axial section of the having the same diameter as the shaft ele structure after the crane has brought the ment in the offset column, which depend-first items onto the platform; 70 ing shaft element passes through the plat Figure 10 shows a second embodiment form and can even project below it The of a device for raising the shaft in the offset shaft element rising from the column comes column; and into contact with this downwardly extend Figure 11 shows, on a larger scale, the ing shaft element and the two shafts are method of fixing the shaft on the offset 75 then rigidly joined together end to end column.

After this joining, the shaft assembly con In Figure 1, the finished base 1 is placed tinues to rise until the crane has reached on the underwater bed at level 0, and a its required height The shaft assembly is central shaft 2 constituting a column for then united with the upper edge of the off supporting the platform, together with a 8 () set column and with the edge of the hole cylindrical wall 3 (shown schematically), which provides a passage for the joined and an offset column 4, rise up to the reshafts through the platform quired level 5 of the platform, which has The raising of the shaft element in the not yet been brought into position For this offset column may be done by means of reason, the structure is still partly under 85 jacks which cooperate with toothed racks ballast to obtain a free-board 6 adapted to arranged on the inside walls of the offset possible movements of the later line.

column It can alternatively be done by In the offset column 4, there has almeans of a block and tackle suspended on ready been placed a sliding shaft element the base of the crane, the cable at which 7 the base of which carries four equally 9 () may be wound on the crane windlass In spaced jacks 8 (see Figure 2) resting on this event, the shaft element in the offset the teeth of racks 9 attached to the inside column features pulleys on its base, over face of the offset column 4 The jacks 8 the which the cables pass, the ends of which attached to lugs 10 projecting downwardly cables are fixed, on the one hand, to the below an inwardly-turned flange 11 which 95 inside wall of the column, near its upper partially closes the lower end of the shaft edge, and, on the other hand, to a central element 7 The direction of the jacks 8 is ring intended for hooking on to the block slightly inclined outwards under the acand tackle tion of springs 12 which are braced against The invention embraces the base, the the flange 11 and against brackets 13 which 100 transportable platform and the complete are parts of the jacks 8 Small sockets 14 installation as defined in the appended on the brackets 13 ensure that the springs claims are centred.

The following description with respect to The number of jacks can vary, but it will the attached drawings, given as a non always be an even number, and the assem 105 limiting example, will explain how the in bly of jacks is distributed in an even manvention can be carried out, characteristics ner around the flange 11 In the described which emerge from the drawings as well as embodiment, this number has been limited from the text forming, of course, a part to four but, in fact, the number is mainly of the said invention a function of the dimension of the support 1 l( 1 In the drawings: ing flange 11 (see also Figure 3).

Figure 1 shows an axial section of the The end of the piston rod of each jack base of the platform structure; is provided with a pawl 15 which engages Figure 2 shows an axial section through on one of the teeth of the rack 9 on the part of the offset column; inside of the column 4 As can be seen 1 i 5 Figure 3 shows a section along the line from Figure 3, these racks are provided III-III of Figure 2; with fixing devices 16 which are embedded Figure 4 shows an axial section of the in the concrete of the offset column 4 There platform structure just before the position can also be seen in Figure 3 slide rails 17 ing of the platform on a central shaft up which are fixed by hooks 18 and which are 120 standing from the base of the platform slightly proud of the inside face 19 of the supporting column; column 4.

Figure 5 shows, schematically, the plat The shaft element 7 is centred by these form; rails 17, thus reducing the total frictional Figure 6 shows the platform at the force and ensuring the correct function 125 moment of centring it above the central ing of the rack device.

shaft; Figures 4 to 6 show a preferred method Figure 7 shows an axial section of the of positioning the platform 20 on the base shaft assembly and the top of the offset 1, in such a manner that once this operacolumn after fixing of the shaft elements; tion is finished, the crane 21 can be raised 130 1 572 545 to the required height in a short time so as to contribute to the -assembly of installations on the platform.

The vertical section shown in Figure 4, and in which the cylindrical wall 3 is again indicated schematically, shows the platform placed on a catamaran 22 made up of two barges 23, onto each of which is placed a supporting scaffolding structure 24 These scaffolding structures permit the platform to be maintained slightly above its required level 5, so that it can be manoeuvred, passing above the central shaft 2 and the offset column 4 This position can be clearly seen in Figure 4.

Turning to Figure 5 it is possible to follow the different stages for satisfactorily controlling this operation The two barges 23 are connected together by two crosselements 25 a, 25 b Windlasses (not shown) are installed on the barges, with which, with the help of cables 26 fixed to the cylindrical wall 3, it becomes possible to control the approach of the catamaran and to achieve its precise centring and direction with respect to the base 1, in particular to align a seating area of the platform with the shaft 2 and to bring the crane 21 over the offset column 4.

In the course of this manoeuvre, one of the cross-elements, such as 25 b, is temporarily removed and replaced after the prows of the barges have passed the tops of the shaft 2 and offset column 4 Up to the termination of this stage of the operation, it is also preferable to lower the boom 27 of the crane 21 and to direct it towards the centre of the platform (as shown at 27 a), and even to rest it on the platform in order to lower further the centre of gravity of the assembly.

After the centring of the platform 20 with respect to the base 1, the latter is lightened by pumping ballast water until the upper edges of the central shaft 2 and the offset column 4 come into contact with the lower face of the platform 20 The consequence of this unballasting is the raising of the platform 20, the entire weight of which, from now on, rests on the central shaft 2.

During the completion of this manoeuvre, it is already possible to start another operation, namely that intended to raise the crane to the desired height on the platform The jacks 8 start to operate alternately in pairs, each time a pair of diametrically opposed jacks being operated together.

It may be advantageous to stagger the levels of the supporting surfaces 28 of the teeth of the racks 9 of one pair with respect to the other On pressurising the upper chambers of the jacks 8, the two pawls of which are first supported by the surfaces 28, the bottom of the shaft element 7 is raised until the piston 8 a of each jack reaches the position indicated on the right of Figure 2.

At this moment, another pair of jacks is brought into operation, and, once their 70 pawls 15 have engaged surfaces 28 of the rack and their upper chambers have been pressurised, not only do the pawls of the first pair of jacks 8 slide upwards under the action of the jacks whose pistons are 75 approaching the finish of their strokes, but by pressurising the lower chambers of the first pair of jacks, their pawls are moved upwards by a larger step (left part of Figure 2) XV In this manner, the shaft element 7 slowly rises to meet another shaft element 29 which extends downwardly from the support plate 30 on which the crane is mounted 85 Figure 7 shows the joining of these two shaft elements 7 and 29 Each of them is provided with an internal flange, 31 for shaft element 7, 32 for shaft element 29, at the end which has to be brought together 90 with the other These flanges 31 and 32 are joined by bolts 33 Man holes and ladders (not shown) inside these shaft elements give access to personnel to the joining area, and even to the jacks to permit their 95 maintenance.

After the joining of the shaft elements 7 and 29 by means of the flanges 31 and 32 has been carried out, the temporary attachments, which have held the crane 100 during the transporting of the platform 20, are removed and the assembly of the shaft elements, which now form a unit, can be resumed The assembled shaft, centred below by the slide rails 17, is guided 105 upwards by a guide ring 34 fixed to the platform, and the crane rises as can be seen in Figure 8 When the shaft has reached the required height, it is positively fixed at the bottom to the upper end of 11 ( the column 4 and at a higher point to the centring ring 34.

The lower fastening is made first It comprises a ring made up of two halfcircles ending on their upper parts in radial 115 rims 35, by which rims the two half-circles are joined together by bolts 36 The lower part of each half-circle 37 has a radial flange on each side, one flange 37 a extending inwardly and the other flange 37 b ex 120 tending outwardly The internal flange 37 a is connected by bolts 38 to the flange 11 of the shaft element 7, whilst the external flange 37 b is bolted by bolts 39 to a flange which is integral with the column 4 125 An upper connection 41 is put in place subsequently The only purpose of this connection is to transmit shear forces in the horizontal plane to the ring 34 fixed to the platform (which is only indicated by the 130 1 572 545 horizontal line 5) The connection 41 is also made up of two half-circles which serve to centre the lower shaft element 7, and is fixed directly to the ring 34 by bolts and nuts 42.

Figure 9 shows the crane 21 in its final position, having already started to assemble installations on the platform.

Another possible means for bringing together the two shaft elements one to the other is illustrated in Figures 10 and 11.

In this case, the windlass of the crane is used for carrying out the raising of the shaft element 7 The principle of this systern will be explained by referring to Figure 10.

To the flange 11 of the lower shaft element 7 a certain number of pulleys 50 are fixed by means of supports 51 A cable 52 passes round each pulley, one end of which cable 53 is attached to the inside of the column 4, near its upper edge, the other end being attached to a connection piece 55 to which are attached all the ends 54 of the cables 52.

The connection piece 55 comprises a central ring 56 This piece is suspended from a hook 57 attached to the lower block 58 of a block and tackle 59, the dead end of the cable 60 being attached to an eye 61 on the support 30 of the crane 21, whilst the other end is actuated by a windlass 62.

In this embodiment, the block and tackle is designed to be able to raise a maximum load of between 1000 and 1600 tons During the erection manoeuvre, the position of the boom 27 will be brought as near the vertical as possible to reduce the decentralisation of the centre of gravity.

It being understood that the weight of the type of cranes used on the bridge varies normally between 1500 and 3000 tons, it suffices to use blocks intended for 1 5 to 2 times the number of turns that can be taken around on the windlass.

The block and tackle can be recovered, when, the two shaft elements are joined together and fixed on the offset column 4, in the same manner as that indicated earlier on The windlass 62 can now return to operating the crane cable.

The embodiments described have only been given as examples and they can be modified, notably by the substitution of equivalent techniques, without departing from the scope of the invention as defined in the appended claims.

Claims (16)

WHAT WE CLAIM IS: -

1 A method of installing a crane for use on a platform structure over water, the platform structure seating upon a supporting column which is part of a base resting on the water bed, the method including the steps of installing the crane and a mounting therefor upon the platform structure offset from the column-seating area thereof for deck use over and alongside the platform structure, transporting the platform structure to the site of the 70 base and positioning the platform structure to seat upon the column of said base with the crane mounting aligned with a subsidiary offset column in the base, and elevating the crane to a final functional 75 position above the platform structure by raising a shaft in said subsidiary column, which shaft engages the crane mounting.

2 A method according to claim 1, wherein the shaft in the subsidiary column 8 () is first raised to engage a matching shaft which is a depending part of the crane mounting and is further raised to elevate the crane when the mutually engaged shafts have been fastened together 85

3 A method according to claim 1 or 2, wherein the shaft in the subsidiary column is raised by jacks which are attached to said shaft and which actuate pawls engaging racks inside the subsidiary go column.

4 A method according to claim 1 or 2, wherein the crane windlass is used to raise the shaft in the subsidiary column with the aid of block-and-tackle gear and 95 cables extending through said shaft and around pulleys to the inner face of the subsidiary column.

A method according to any one of the preceding claims, wherein the shaft in 10 ( the subsidiary column when raised to elevate the crane is held raised by a fastening to the subsidiary column.

6 A platform installation comprising a base resting upon the bed of a body of 105 water and a platform structure which carries a crane and a crane mounting and is adapted to be seated upon a supporting column rising from the base, characterised by a subsidiary offset column rising from 110 the base and including a crane-elevating shaft which can be raised to engage a shaft depending from the crane mounting and to lift the crane to an elevated position above the platform structure It S

7 A base for supporting a crane-carrying platform structure over water, the base resting on the water bed and having a column upon which the platform structure may be seated, characterised by a subsidiary 120 offset column embracing a vertical shaft, and jacking means for raising the shaft to engage and lift a crane mounting on the platform structure for the purpose of elevating the crane above the platform struc 125 ture.

8 An installation according to claim 6, or a base therefor according to claim 7, wherein racks are fitted to the inner face of the offset column for use in raising the 130 1 572 545 crane-elevating shaft, the racks alternating with shaft-guiding slide rails around the periphery of said inner face.

9 An installation or a base according to claim 8, wherein two or more pairs of jacks extend from the bottom of the elevating shaft to cooperate with the racks.

An installation or a base according to claim 9, wherein the jacks are doubleacting and operate pawls to climb the racks.

11 An installation according to claim 6, wherein for raising the crane-elevating shaft in the offset column, pulleys are mounted at the bottom of said shaft over which pulleys cables pass from the wall of the offset column, near the upper edge thereof, to the upper end of said shaft for hooking to block-and-tackle gear on the crane mounting.

12 An installation according to claim 11, wherein block-and-tackle gear on the crane mounting is adapted to be operated by the windlass which normally serves for winding the crane cable.

13 A crane-carrying platform structure for use over water and providing for deck use of a crane over and alongside the structure during transportation and installation of the structure and for use elevated above the structure when the latter has been positioned over and seated upon a column upstanding from a base resting on a water bed, characterised by a crane mounting offset from the seating area, the crane mounting including a downwardly extend 35 ing shaft which for deck use of the crane passes through the structure and can be raised through and clear of the structure by jacking means In the base when the structure has been positioned and seated 40

14 A crane-carrying platform structure substantially as described with reference to Figures 4 to 6, 8 and 9 of the accompanying drawings.

A crane-carrying platform installa 45 tion or a base therefor substantially as described with reference to the accompanying drawings.

16 A method of installing a crane on a platform structure for use over water 50 substantially as described with reference to the accompanying drawings.

ARTHUR R DAVIES Chartered Patent Agents, 27, Imperial Square, Cheltenham.

and 115, High Holborn, London, W C 1.

Agents for the Applicants.

Printed for Her Majesty's Stationery Office by The Tweeddale Press Ltd, Berwick-upon-Tweed, 1980.

Published at the Patent Office, -25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.